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| Titel |
Eddy covariance flux measurements of pollutant gases in urban Mexico City |
| VerfasserIn |
E. Velasco, S. Pressley, R. Grivicke, E. Allwine, T. Coons, W. Foster, B. T. Jobson, H. Westberg, R. Ramos, F. Hernandez, L. T. Molina, B. Lamb |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 19 ; Nr. 9, no. 19 (2009-10-02), S.7325-7342 |
| Datensatznummer |
250007663
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| Publikation (Nr.) |
 copernicus.org/acp-9-7325-2009.pdf |
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| Zusammenfassung |
| Eddy covariance (EC) flux measurements of the atmosphere/surface exchange of
gases over an urban area are a direct way to improve and evaluate emissions
inventories, and, in turn, to better understand urban atmospheric chemistry
and the role that cities play in regional and global chemical cycles. As
part of the MCMA-2003 study, we demonstrated the feasibility of using eddy
covariance techniques to measure fluxes of selected volatile organic
compounds (VOCs) and CO2 from a residential district of Mexico City
(Velasco et al., 2005a, b). During the MILAGRO/MCMA-2006 field campaign, a
second flux measurement study was conducted in a different district of
Mexico City to corroborate the 2003 flux measurements, to expand the number
of species measured, and to obtain additional data for evaluation of the
local emissions inventory. Fluxes of CO2 and olefins were measured by
the conventional EC technique using an open path CO2 sensor and a Fast
Isoprene Sensor calibrated with a propylene standard. In addition, fluxes of
toluene, benzene, methanol and C2-benzenes were measured using a
virtual disjunct EC method with a Proton Transfer Reaction Mass
Spectrometer. The flux measurements were analyzed in terms of diurnal
patterns and vehicular activity and were compared with the most recent
gridded local emissions inventory. In both studies, the results showed that
the urban surface of Mexico City is a net source of CO2 and VOCs with
significant contributions from vehicular traffic. Evaporative emissions from
commercial and other anthropogenic activities were significant sources of
toluene and methanol. The results show that the emissions inventory is in
reasonable agreement with measured olefin and CO2 fluxes, while
C2-benzenes and toluene emissions from evaporative sources are
overestimated in the inventory. It appears that methanol emissions from
mobile sources occur, but are not reported in the mobile emissions
inventory. |
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